A shared band of spectrum may be managed directly by the regulator, or this responsibility may be delegated in large part to a license-holder. New forms of spectrum sharing that greatly improve spectral efficiency and alleviate scarcity, if policies are in place that support these forms of sharing. On the other hand, new technology that is inconsistent with spectrum policy will have little impa...

Cognitive radio is a means to solve the spectrum scarcity problem by allowing secondary spectrum users to share channels with the primary spectrum users in an opportunistic fashion. However, cognitive radio requires high costs in terms of spectrum sensing and monitoring system complexities as well as potential interference issues to the primary spectrum users. In this paper, we propose a spatia...

Cognitive radio networks provide an opportunity for unlicensed users (secondary users) to use the allocated spectrum band when not in use by legitimate users (primary users). To use a channel or spectrum, it is required to sense the channel for the presence of primary user which is called Spectrum Sensing. In order to reduce the sensing time of spectrum and to determine the state of the channel...

Dynamic spectrum access is an important way to alleviate the spectrum scarcity. Traditionally, secondary users are allowed to opportunistically operate when primary users are absent and buy idle bands from primary users. Although it improves the spectrum utility to some extents, it is not enough. In this paper, we argue that spectrum hole should be endogenous which means they should be negotiat...